First, line an 8x8 inch square baking pan with parchment or waxed paper, making sure to lightly grease the paper. This helps prevent sticking.
Pour the sugar-free condensed milk into a medium saucepan. Place it over medium-low heat and stir continuously until it just begins to simmer. Once it starts simmering, immediately take the pan off the heat.
Add the sugar-free chocolate chips and your keto Nutella to the warm condensed milk in the saucepan. Let it sit for a few minutes to soften, then grab a whisk and stir everything together until it's completely smooth and wonderfully combined.
Now, stir in your chosen sweetener, collagen protein powder, and the hazelnut extract. Mix well until the mixture is super smooth and all ingredients are fully incorporated.
Gently fold about two-thirds of your chopped toasted hazelnuts into the rich fudge mixture. These add a delightful crunch!
Pour the prepared fudge into your lined pan, spreading it evenly to the edges. Sprinkle the remaining chopped hazelnuts over the top for a pretty finish. Pop it into the refrigerator for 3 to 4 hours to let it firm up nicely.
Once the fudge is firm, use the paper edges to lift it out of the pan and onto a cutting board. Grab a large, sharp knife and cut your delicious fudge into 16 perfect bars.